Circulatory System 10.1

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ARTERIES

• Arteries-blood vessels that carry blood away

from the heart

▫ Thick walls

▫ Inner & Outer layers: connective tissue

▫ Middle layers are muscle and elastic

connective tissue

▫ Stretch to accommodate the in-rush of blood

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ARTERIOLES

• Blood from the arteries passes into smaller

blood vessels carrying blood away from the

heart named ARTERIOLES.

• The middle layer of the arteriole blood

vessels are made up of elastic fibres and

smooth muscle.

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Source:

http://www.tiscali.co.uk/reference/encyclopaedia/hutchinson/images/0008n031.jpg

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• Smooth muscle relaxes,

causing the walls of the

artery to dilate,

increasing blood flow

(vasodilation)

▫ Blushing, releases heat

• Nerve impulse causes the

smooth muscle in the

artery to contract,

reducing diameter of the

vessel and decreasing

blood flow.

(vasoconstriction)

▫ Turn pale when frightened

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Atherosclerosis

• Excess lipids in the blood is deposited on the

walls of the arteries

• Minerals like calcium deposit on top of the

lipid forming plaque

• Narrows arteries and causes high blood

pressure

• Plaque penetrates artery walls, causing

blood clots to form

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Artherosclerosis

Source: http://www.nlm.nih.gov/medlineplus/ency/imagepages/18020.htm

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Aneurysm

• Bulge that forms in a weakened blood vessel

• Due to artherosclerosis

• Weakened bit of artery protrudes as blood is pumped through

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Capillaries

• Single layer of cells

• Fluid and gas exchange

• Capillary beds are easily damaged

• High blood pressure or impact will rupture

the capillary

• Oxygen is diffused from the blood to the

tissue through the walls of the capillaries

• Oxygenated blood=red

• Deoxygenated blood= deep purple/red

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Veins and Venules

• Capillaries merge and become larger

vessles called venules

• Walls of venules contain smooth muscles

• Venules merge to form veins

• Blood passes through narrow vessels with

weaker walls, pressure is reduced

• When blood reaaches venules, the pressure

is too low to drive blood back to the heart

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Valves

• One way valves, directing blood back to the

heart

• Skeletal muscles bulge when in use,

reducing the diameter of the vein

• Pressure in the vein increases, the valves

open allowing blood to flow towards the

heart

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Veins

• 65% of your blood is stored in the veins

• Varicose veins

▫ Veins distend and blood pools in the veins and

damages the valves

▫ Blood seeps through the one way valves and

stays collects

▫ Prolonged standing or compressing the veins

(sitting crossed legged) can contribute to the

problem

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Vericose Veins

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Questions

• Pg. 316

▫ 1-3

• Pg. 318

▫ 1, 3, 5, 7

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The Heart 10.2

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Heart

• Pericardium-fluid filled sac that surrounds

the heart, prevents friction

• 4 chambers

• 2 thin walled atria

▫ (chamber that receives blood from the veins)

• 2 thick walled ventricles

▫ (chamber that delivers blood to the arteries)

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Pumps

• 2 parallel pumps are separated by the

septum (wall of muscle). The septum keeps

the oxygenated blood separate from the

deoxygenated blood.

• Pump on the right

▫ Receives deoxygenated blood from the body

and pumps it into the lungs

• Pump on the left

▫ Receives oxygenated blood from the lungs

and pumps it into the body

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Pulmonary Circulatory System

• Blood vessels that carry blood to and from the lungs

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Systemic Circulatory System

• Vessels that

carry blood to

and from the

body

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• Superior vena cava carries deoxygenated

blood from the head and upper body to the

right atrium

• Inferior vena cava carries deoxygenated

blood from all veins below the diaphragm to

the same atrium

• Pulmonary veins carry oxygenated blood

from the lungs to the left atrium

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• Atrioventricular

valves (AV) separate

the atria from the

ventricles

• AV prevent blood

from backflowing

from a ventricle into

an atrium

• Semilunar valves

(SV) separate he

ventricles from the

arteries

• SV prevent blood

from backflowing

from an artery into a

ventricle

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• Aorta carries oxygenated blood away from

the heart

• Coronary arteries supply the muscle cells in

the heart with oxygen and nutrients

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Coronary Bypass Surgery

• Cardiopulmonary bypass

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Artificial Heart

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Cardiac Catheterization

• Catheter is inserted in artery in the groin

• Pushed through aorta into the heart

• Radioactive dye is injected into catheter

• Dye travels through blood vessels, where

restrictions can be seen

• Angioplasty, using an inflatable balloon to

open the blockage

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Angioplasty

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Heartbeat

• Contracts without being stimulated by external nerves (myogenic muscle)

• Beat rate is set by the sinoatrial (SA) node • Upper right atrium sets a rhythm at about 70

bpm • Contractions travel to second node,

atrioventricular (AV) node, which acts as a conductor

• (AV) node passes impulses via 2 Purkinje fibres to the bottom of the heart

• L and R atria contract before the L and R ventricles

Simulation of Heart Pumping

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Heart Sounds

• Closing of the valves causes the lubb dubb

• Diastole is the period of rest when the atria

and ventricles are relaxed

• Atria fill with blood while they are relaxed

• Atria contract, increasing pressure, forcing

the AV valves open

• Blood flows from atria into ventricles

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• Filled ventricles contract, pressure forces

AV valves shut, producing lubb sound and

pushing blood into the arteries

• Period of contraction is called systole

• Ventricles relax, volume increases

• Increased volume, pressure in ventricles

decreases, closing of semilunar valves

creates dubb sound

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Check your understanding

• Pg. 327

• Questions 1, 2, 5 & 6

• Label heart diagram

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